Electrodeposition of nickel



United States Patent The Udylite Corporation, Warren, Mich, a corporation.

of Delaware N0 Drawing. Filed Dec. 6, 1960, Ser. No. 73,985

13 Claims. (Cl. 204-49) This invention relates to the electrodeposition of nickel from aqueous acidic baths. 7

One object of this invention is to produce semi-bright, sulphur-free, fine-grained columnar structured nickel plate of high corrosion resistance to salt solution or spray.

A second object is the production of fully bright nickel plate.

It has definitely been established by outdoor exposure tests that chromium plated nickel plate has superior corrosion resistance in marine atmospheres when the underlying nickel is a sulphur-free type, as for example, the nickel plate from a plain Watts type nickel bath. However, the latter plate is too dull, that is its grain size too large when plated in thicknesses of about 25 microns (1 mil) for easy buffing to a high luster, and also too dull to be brightened to full luster by plating bright nickel of approximately 10 to 25 microns over the dull nickel. Thus, there is an important need for a ductile, fine-grained columnar structured sulphur-free nickel plate that can be consistently obtained of high quality without the need of batch activated carbon treatments of the bath.

We have now found that by using about 0.01 to about 0.15 grams per liter, of one or more of certain unsaturated glycol ether compounds shown in Table I in Watts type nickel baths, in conjunction with about 0.05 to 0.3 gram per liter of chloral hydrate and/ or bromal hydrate, it is possible to obtain fine-grain ductile sulphur-free nickel plate of columnar structure over a wide range of cathode current densities. Chloral and bromal hydrates are, however, too volatile from the warm air agitated baths (e.g. 55-65 C.) when used in concentrations higher than 0.25 to 0.3 gram per liter, and we have found that it is possible to use from 0.02 to 0.12 gram per liter of formaldehyde in conjunction with the lower concentrations (0.05 to 0.25 gram per liter) of chloral and bromal hydrates, even though formaldehyde itself does not cooperate with the compounds of Table I nearly to the extent that the halogenated aldehydes do, to give uniform semi-bright late. P The compounds of Table I produce only small per- 3,140,988 Patented July 14, 1964 centages of harmful breakdown products with con-tinned electrolysis and these are readily removed by small amounts of activated carbon kept in the filters. The compounds of Table I are not appreciably removed by the activated carbon. Only about 500 to 1,000 grams of activated carbon per 5,000 liters is necessary and the carbon needs to be changed only once per week. Chloral hydrate, bromal hydrate and formaldehyde produce no harmful breakdown products with continued electrolysis and are not appreciably removed by the activated carbon kept in the filter. Bromal hydrate is, however, adsorbed by the carbon to a somewhat greater extent than chloral hydrate, but since it is used at low concentrations, the loss by this method is not too serious.

Thus the use in Watts bath of the combination of these aldehydes with the compounds of Table I produce an outstandingly consistent ductile semi-bright sulphur-free nickel plate of columnar structure. It is preferred for obtaining the widest plating range of fine-grained ductile semi-bright plate to use high concentrations of nickel sulfate in the Watts bath, that is, 300 to 400 grams per liter. Actually the nickel sulfate concentrations can approach the saturation values at the temperature of the bath, though this is not practically desirable, as a lowering of the bath temperature will cause crystallization. It is also impractical to use concentrations of nickel sulfate below about 100 grams per liter, because this lowers appreciably the limiting cathode current density. The nickel chloride concentration when used as the sole source of nickel salt may be 100 grams per liter, but the ductility of the plate is not nearly as good as from the Watts bath.

. In the Watts bath, the best concentrations of nickel chloride (NiCl -6H O) to use is about 45 to about grams per liter. Higher concentrations of nickel chloride tend to decrease the ductility and also to dull the low current density areas.

The preferred compounds of Table I are Examples 1 and 2. The efficacy of these compounds, which are the reaction products of epichlorohydrin and butyne diol, is surprising in view of the fact that butyne diol itself does not improve the low current density areas when used in conjunction with chloral hydrate, bromal hydrate or formaldehyde or mixtures. It was found, however, that while 0.01 to 0.1 gram per liter of Z-butene, 1,4-dio1 does help to improve the low current density areas it does not do so to the extent accomplished by Examples 1-4 of Table I. The lower concentrations of addition agents shown in Table I are suitable to be used with the higher bath temperatures and the more rapid solution agitation.

OH OH (8) CICHflHCHZOCHQ CH=CHCHZOCHQHCHflCl (9) HOCHCH=CHCII1OC1H4OH (l0) HOCal-I40CHzCH=CH-CHOC H4OH The unsaturated glycol ether compounds of Table I can be further classified by the following formula:

111-0 onl-o z o-orno R,

in which Z is a linkage selected from the group of double and triple bonds, x is a numeral which is 0 when Z is a triple bond and 1 when Z is a double bond, R is a radical selected from the group consisting of and R is a radical selected from the group consisting of It was also found that Examples 1 to 6 inclusive when used in conjunction with allyl sulfonic acid in concentrations of 0.3 to 10 grams per liter gave very bright, good leveling nickel plate of excellent covering power. The excellent bright covering power was only obtained with allyl sulfonic acid (or Na or Ni salt) and not with other alkene sulfonic acids such as vinyl sulfonic acid or butene sulfonic acids, or with aryl sulfonic acids such as naphthalene or benzene sulfonic acids. The usual aryl sulfonic acids or sulfonamides or sulfonimides (like benzene sulfonic acids, naphthalene sulfonic acids or o-benzoyl sulfonimide) also may be present, but the excellent bright covering power is obtained only when the allyl sulfonic acid is also present in Watts or bright nickel chloride baths (up to 300 grams/liter of nickel chloride). This type bright nickel was excellent to cover the semi-bright nickel with a minimum of adhesion troubles. The semibright nickel plate of this invention can be transferred directly to this bright nickel bath to thus form a composite plate of semi-bright sulphur-free nickel and bright nickel without any dulling or adhesion problems because of the excellent compatibility of all the addition agents involved.

Examples A, B and C set forth below are typical examples of suitable baths and conditions for producing semibright sulphur-free nickel plate, but it is to be understood that any of the other specific compounds from Table I in its indicated concentration could be substituted for the Table I compound enumerated therein. ExampleD sets forth suitable conditions and ingredients to form fully bright plate.

Example A Grams/liter NiSO -6H O 200-400. NiCl -6H O 30-60 (opt. 45-50). H BO 40-45. pH 3.5-4.8. Temp 5065 C.

HOCH C l ECCH OCH CHCH CL 0.03-0.06. Formaldehyde 0.02-0.04. Chloral hydrate 0.08-0.12.

Average cathode current densities 2-6 amps./ sq. drn.

Useful Cone, grams/liter Example B NiSOy 6H O 150-400. NiCl 6H O 30-50. H BO 40-45. pH 3.8-4.5. Temp 5065 C.

OH OH I ClCH CHCI-l OCH C l ECCH2OCH2CHCH2CL. 0.03-0.03.

Formaldehyde 0.02-0.08. Chloral hydrate 0.05-0.12. Average cathode current densities 2-6 amps/sq. ClIIl.

Example C NiCl '6H O 40-50. H BO 40-45. pH 3.8-4.5. Temp 55-63 C. HOCH CEC-CH OC H OH 0.03-0.06. 2-butene 1,4-diol 0.02-0.04. Formaldehyde 0.02-0.08. Chloral hydrate 0.050.l2. Bromal hydrate 0-0.l. Average cathode current densities 2-6 amps/sq. drn.

Example D For the electrodeposition of full bright deposits:

Grams/liter NiSO 6H O 50-400. NiCl -6H O 250-30.

H BO 40-45. Any one or more of Examples 1-6 of Table 1, total concentration 0.050.25. Allyl sulfonic acid (Ni or Na salt) 0.3-10.

pH 3.0-4.8. Temp 50-65 C. Average current densities 2,-10 amps./sq. dm.

The semi-bright plate obtained from Example A can be transferred directly to the fully bright nickel plating bath D, and when the ratio of the semi-bright plate to the full 'bright'plate is from 50% to of the total plate and the thickness of the total plate is 25 microns (1 mil) or more, excellent outdoor corrosion resistance is obtained with the usual 0.01 mil final chromium plate.

The baths as exemplified by A, B and C can be operated with or Without air agitation. Air agitation or cathode rod agitation is preferred. With air agitation it is often advantageous to use from 0.1 to 1 gram/liter of a non-foaming surface-active agent such as sodium 2-ethyl hexyl sulfate or a mixture of this surface-active agent with a lower concentration of a longer chain surfaceactive agent such as sodium lauryl sulfate. The use of air agitation allows higher current densities to be used.

The use of fluoboric acid or sodium or nickel fluoborate is often desirable When pH value of 4.2 to 4.8 are used. About 0.2 to 3 grams/liter of nickel fluoborate will keep low concentrations of ferric salts from precipitating out at these pH values, and causing settling roughness. The pH values can be from about 3.0 to 5.0, with the best results at about 3.8-4.8. The temperature of n LIP- r the baths may be from 45-70 C. but the preferred temperature range is from about 4863 C.

The best use for the baths exemplified by A, B and C is where the nickel plated article is destined for outdoor use in a corrosive industrial atmosphere and especially in a marine exposure. For example, for exterior hardware and trim on automobiles, for boat hardware, and also for hardware used on laboratory furniture. The semi-bright sulphur-free nickel can be readily buffed to a high luster, or better yet it can be plated with fully bright nickel plate, eliminating the need of a bufiing operation. For the best corrosion protection of the underlying basis metal (steel, zinc castings, brass, copper, aluminum, magnesium, etc.) the semi-bright nickel plate should constitute at least 50% of the total nickel plate, and the total thickness of the composite plate of semibright sulphur-free nickel and bright nickel should be at least 25 microns (1 mil) thick. The final chromium plate need be only 0.13 to 0.25 micron (0.005 to 0.01 mil) thick.

Compounds 1 and 2 are made by the acid catalyzed reaction of 2-butyne-l,4-diol with epichlorohydrin. The preferred acid catalyst is boron trifluoride (Lewis acid). Compounds 3 and 4 are made by the interaction addition of ethylene oxide with 2-butyne-1,4-diol preferably under very mild alkaline conditions such as 0.05% caustic in relation to the weight of butyne diol used. Alternatively, compounds 3 and 4 can be made by the interaction of ethylene chlorohydrin or ethylene bromohydrin, with the di-sodium salt of 2-butyne-l,4-diol dissolved in alcohol. The butyne diol is dissolved in the alcohol before the sodium salt is formed. Compounds 5 and 6 are prepared in a way similar to compounds 3 and 4 except that propylene oxide is used instead of ethylene oxide.

This application is a continuation-in-part of co-pending application, Serial No. 16,176, filed March 21, 1960.

What is claimed is:

l. A bath for electrodepositing lustrous nickel comprising an aqueous acidic solution of pH range of about 3 to about 5.5 containing an electrolyte selected from the group consisting of nickel sulfate, nickel chloride and a mixture of nickel sulfate and nickel chloride and containing dissolved therein in concentrations of about 0.01 to about 0.15 gram per liter at least one unsaturated glycol ether compound represented by the formula in which Z is a linkage selected from the group consisting of double and triple bonds, x is a numeral which is 0 when Z is a triple bond and 1 when Z is a double bond, R is a radical selected from the group consisting and R is a radical selected from the group consisting of and a halogenated aldehyde selected from the group consisting of chloral hydrate and bromal hydrate in a concen tration of about 0.05 to about 0.3 gram per liter.

2. A bath for electrodepositing lustrous nickel comprising an aqueous acidic solution of pH range of about 3 to about 5.5 containing an electrolyte selected from the group consisting of nickel sulfate, nickel chloride and a mixture of nickel sulfate and nickel chloride and containing dissolved therein in concentrations of about 0.01 to about 0.15 gram per liter at least one unsaturated glycol ether compound represented by the formula in which Z is a linkage selected from the group consisting of double and triple bonds, x is a numeral which is 0 when Z is a triple bond and 1 when Z is a double bond, R is a radical selected from the group consisting OH CH3 H, oH, 1HoH,o1, -0,H,0H and oH,t JHoH and R is a radical selected from the group consisting of 0H CH5 -oH,bHoH,o1, -o,H,oH and oHir JHoH and a halogenated aldehyde selected from the group consisting of choral hydrate and bromal hydrate in a con- "centration of about 0.05 to about 0.3 gram per liter and formaldehyde in a concentration of about 0.02 to about 0.12 gram per liter.

3. A bath in accordance with claim 2 wherein the electrolyte consists of a mixture of nickel sulfate in a concentration of about grams per liter to about saturation, and nickel chloride in a concentration of about 30 to 60 grams per liter, and the temperature range of the bath is from about 45 C. to 70 C.

4. A bath in accordance with claim 2 wherein the electrolyte consists of a mixture of nickel sulfate in concentrations of about to 400 grams per liter, and nickel chloride in concentrations of about 30 to 60 grams per liter, and the temperature range of the bath is from about 45 C., to 70 C., said bath containing dissolved therein about 0.01 to about 0.15 gram per liter of at least one compound represented by the formula where Z is a triple bond.

5. A method for electrodepositing lustrous nickel which comprises the step of electrodepositing nickel from an aqueous acidic nickel bath of pH range of about 3 to 5.5 consisting essentially of an electrolyte selected from the group consisting of nickel sulfate, nickel chloride, and a mixture of nickel sulfate and nickel chloride, and containing dissolved therein about 0.01 to about 0.15 gram per liter of an unsaturated glycol ether compound represented by the formula in which Z is a linkage selected from the group consisting of double and triple bonds, x is a numeral which is 0 when Z is a triple bond and 1 when Z is a double bond, R is a radical selected from the group consisting of OH (3H3 -H, -CHzHCHzC1, C2H4OH, and 'CHZHOH and R is a radical selected from the group consisting of and a halogenated aldehyde selected from the group consisting of chloral hydrate and bromal hydrate in a concentration of about 0.05 to about 0.3 gram per liter.

6. A method for electrodepositing lustrous nickel which comprises the step of electrodepositing nickel from an aqueous acidic nickel bath of pH range of about 3 to 5.5 consisting essentially of an electrolyte selected from the group consisting of nickel sulfate, nickel chloride, and a mixture of nickel sulfate and nickel chloride, and containing dissolved therein about 0.01 to about 0. l5 gram per liter of an unsaturated glycol ether compound represented by the formula H, -ornoH-on,c1, o,rt,oH, and -ombnort and R is a radical selected from the group consisting of OH CH1! -CHzC HCHgCl, CnH4OH, and CHg( )HOH and a halogenated aldehyde selected from the group consisting of chloral hydrate and bromal hydrate in a concentration of about 0.05 to about 0.3 gram per liter and formaldehyde in a concentration of about 0.02 to about 0.12 gram per liter.

7. A method in accordance with claim 5 wherein the electrolyte consists of a mixture of nickel sulfate in a concentration of about 100 grams per liter to about saturation, and nickel chloride in a concentration of about 30 to 60 grams per liter, and the temperature range of the bath is from about 45 C. to 70 C.

8. A method in accordance with claim '5 wherein the electrolyte consists of a mixture of nickel sulfate in concentrations of about 150 to 400 grams per liter, and nickel chloride in concentrations of about 30 to 60 grams per liter, and the temperature range of the bath is from about 45 C. to 70 C. and said bath containing dissolved therein about 0.01 to about 0.15 gram per liter of at least one compound represented by the formula where Z is a triple bond.

9. A bath in accordance with claim 1 wherein. said unsaturated glycol ether compound is oH HO CH2OEC0H,oCH,c1-I0H2c1 10. A method in accordance with claim 5 wherein said unsaturated glycol ether compound is 11. A bath in accordance with claim 1 wherein said unsaturated glycol ether compound is 12. A method in accordance with claim 5 wherein said unsaturated glycol ether compound is HOCH CECCH OC H OH halogenated aldehyde selected from the group consisting of chloral hydrate and bromal hydrate.

References Cited in the file of this patent UNITED STATES PATENTS 2,026,718 Weisberg et a1. Jan. 7, 1936 2,900,707 Brown Aug. 25, 1959 FOREIGN PATENTS 1,231,332 France Apr. 11, 1960 

1. A BATH FOR ELECTRODEPOSITING LUSTROUS NICKEL COMPRISING AN AQUEOUS ACIDIC SOLUTION OF PH RANGE OF ABOUT 3 TO ABOUT 5.5 CONTAINIING AN ELECTROLYTE SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE AND A MIXTURE OF NICKEL SULFATE AND NICKEL CHLORIDE AND CONTAINING DISSOLVED THEREIN IN CONCENTRATIONS OF ABOUT 0.01 TO ABOUT 0.15 GRAM PER LITER AT LEAST ONE UNSATURATED GLYCOL ETHER COMPOUND REPRESENTED BY THE FORMULA 